Prerequisites Protocols

Initial Goal

A set of magnetic resonance (MR) and computer tomography (CT) images of the extremity specimen (upper/lower leg, upper/lower arm) with clear visual delineation of skin, fat, and muscle layers.

Additional information about the imaging facility, all associated contacts, and MRI hardware can be found at:

Position/Orient Specimen in MRI Machine

Acquire Image Sequences

For each segment (upper leg, lower leg, upper arm, and lower arm), the following set of image collection protocols will be performed. All images should be acquired in the same coordinate system to be able to align reconstructed tissue geometries during assembly of the full segment geometry. To accomplish this the origin (isocenter) and the axes of the magnet, which is set at the beginning of the session, should not change. In addition, the specimen should not be moved. It should be noted that a pixel-by-pixel alignment of image sets (co-localization) is not necessary.

[Examples to come] Before, each sequence is acquired, verify that the acquisition properties match the desired settings in the tables below. After each sequence is acquired, inspect the images and compare them against the sample images below to to ensure that it was collected properly. If not, the sequence should be recollected.

Final Imaging Specifications

Image Acquisition Properties: Download T1 SettingsDownload PD Settings

T1 w/o Fat Sup

T1 w/ Fat Sup

Proton Density

Plane

Axial

FS

No

Yes

No

Matrix (phase)

389

Matrix (freq.)

512

No. of slices

25

No. of Seq/Segment

4

FOV (mm)

240 x 202.5

Slice thickness/gap (mm/mm)

2/1

Flip angle (deg.)

30

150

TE/TR (ms/ms)

11/500

9.7/4000

Bandwidth (Hz/pixel)

238

222

Chemical shift (pixels)

N/A

No. excitations averaged

1

Turbo Factor

3

Phase encode axis

Anterior-posterior

Distance factor (%)

50%

Phase oversampling

0

Slice oversampling

0

Phase resolution (%)

90

Phase partial Fourier (8/8 = 1)

OFF

Readout partial Fourier (8/8 = 1)

OFF

Slice partial Fourier (8/8 = 1)

7/8

X-resolution (mm)

0.5

Y-resolution (mm)

0.5

Scan Time / Seq. (min.)

~3 min

Imaging Trial 4: 11/30/16

Attendees: Tyler, Rici, Ben (CC), Josh (UH)

SETTINGS 1: Upper Leg

This imaging protocol is similar to Settings 2 - Imaging Trial 2; to acquire axial plane image sets. The in-plane resolution was changed to approximately 0.43 mm and the field of view to 250mm . The out-of-plane resolution remained the same at approximately 3 mm (2 mm slice thickness and 1 mm gap).

The goal is to reduce the shadowing/darkness that appears at the beginning and/or end of a segment. Where a segment is a set number of slices. To achieve this, we tried several different protocols.

Sequence 3 was chosen because of increased image quality due to less slices per segment.

Trial 4 Comparison Sagittal Plane

Comparison of seq#2 to seq#3

Imaging Trial 3 (CT): 11/29/16

Attendees: Tyler, Bong-Jae

SETTINGS 1: Upper Leg

The goal of this imaging session is to provide a set of Computer Tomography (CT) images to compare to MR images of the same specimen used in Imaging Trial 2. Specifically, we want to see if any of the tissue region boundries (skin, fat, muscle) can be more easily delineated.

CT_trial3.png

Imaging Trial 2: 11/16/16

Attendees: Tyler, Ahmet, Rici (CC), Josh (UH)

SETTINGS 1: Upper Leg

The goal of this imaging protocol is to acquire axial plane image sets with an in-plane resolution of approximately 0.47 mm, an out-of-plane resolution of approximately 5 mm (2.5 mm slice thickness and 2.5 mm gap) and a large enough field of view inclusive of the entire axial section of the specimen.

SETTINGS 2: Lower Leg

The goal of this imaging protocol is to acquire axial plane image sets with an in-plane resolution of approximately 0.47 mm, an out-of-plane resolution of approximately 3 mm (2 mm slice thickness and 1 mm gap) and a large enough field of view inclusive of the entire axial section of the specimen.

Imaging Specifications

Sample Image Acquisition Properties:

Settings 1

Settings 2

Imaging Date

11/16/2014

11/16/2014

Plane

Axial

No. of slices

50

50

No. of Seq/Segment

3

4

FOV (mm)

240 x 250

240 x 150

Slice thickness/gap (mm/mm)

2.5/2.5

2/1

No. excitations averaged

1

Distance factor (%)

100%

X-resolution (mm)

0.47

Y-resolution (mm)

0.47

Scan Time / Seq. (min.)

3-4

Imaging Modality

Proton Density

T1

T1

T1 Fat Suppression

Proton Density - Tibia

PD_2nd.png

T1 - Tibia

T1_Lower2nd.png

T1 - Fat Suppression - Tibia

T1_Lower2ndFS.png

Imaging Trial 1: 8/4/16

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Specifications/ImagingDiscussion (last edited 2017-05-09 19:33:19 by schimmt)